Photothermographic element,composition and process

ABSTRACT

A sulfonamidophenol reducing agent in photothermographic elements, compositions and processes provides improved processing temperature latitude. Certain of the sulfonamidophenol reducing photothermographic can be employed in photobermographic materials in the absence of activator toning agents. The photothermographic materials can contain addenda commonly employed in photothermographic materials such as sensitizing dyes, image stabilizers and stabilizer precursors, and various photosensitive compounds.

Evans et al.

Apr. 2, 1974 PHOTOTHERMOGRAPHIC ELEMENT, COMPOSITION AND PROCESSInventors: Francis J. Evans; Donald F.

McLaen, both of Rochester, N.Y.

Assignee: Eastman Kodak Company, Rochester, N.Y.

Filed: July 18, 1972 App]. No.: 272,832

US. Cl. 96/48 HD, 96/66 R, 96/114.1 Int. Cl G03c 5/24, G03c 1/02 Fieldof Search 96/1 14.], 66 R, 94, 48 HD;

References Cited UNITED STATES PATENTS 12/1970 Sagawa 96/94 R 3,734,7265/1973 Figueras et al. 96/3 Primary Examiner-Norman G. Torchin AssistantExaminer-Alfonzo T. Suro Pico Attorney, Agent, or FirmRobert W. Hampton[57] ABSTRACT A sulfonamidophenol reducing agent in photothermographicelements, compositions and processes provides improved processingtemperature latitude. Certain of the sulfonamidophenol reducingphotothermographic can be employed in photobermographic materials in theabsence of activator toning agents. The photothermographic materials cancontain addenda commonly employed in photothermographic materials suchas sensitizing dyes, image stabilizers and stabilizer precursors, andvarious photosensitive compounds.

18 Claims, N0 Drawings PHOTOTHERMOGRAPHIC ELEMENT, COMPOSITION ANDPROCESS BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to certain reducing agents in photothermographicelements, compositions and processes to provide improved processingtemperature latitude with improved neutral developed images. In one ofits aspects it relates to photothermographic elements containing suchreducing agents. In another of its aspects it relates to aphotothermographic composition containing the described reducing agents.A further aspect relates to a method of developinga latent image in thedescribed photothermographic elements by overall heating.

2. Description of the State of the Art It is well known in the art toprovide photothermographic materials containing reducing agents. Suchphotothermographic materials after exposure are heated overall toprovide a developed image in the absence of separate processingsolutions. Reducing agents which have been employed inphotothermographic materials are described, for example, in Belgian Pat.No. 765,452 issued May 28, 1971; Belgian Pat. No. 765,602 issued May 28,1971; Belgian Pat. No. 765,601 issued May 28, 197-1; Belgian Pat. No.766,590 issued June 15, 1971; Belgian Pat. No. 766,589 issued June 15,1971; Belgian Pat. No. 772,371 issued Oct. 15, 1971; U.S. Pat. No.3,152,904 of Sorenson et al. issued Oct. 13, 1964; U.S. Pat. No.3,152,903 of Sorenson et al. issued Oct. 13, 1964; U.S. Pat. No.3,457,075 of Morgan et al. issued July 22, 1969; U.S. Pat. No. 3,392,020of Yutzy et al. issued July 9, 1968 and British Specification No.1,161,777 published Aug. 20, 1969. Many of the reducing agents such asaminophenol reducing agents which have been useful for photographicsilver halide development are overly active in photothermographicmaterials and produce undesired indiscriminate reduction when employedin such photothermographic materials resulting in undesired fog incertain areas of a developed image.

- This is demonstrated in following comparative Example 2. The exposedareas of a photothermographic element tend to rapidly fog if heating ofthe photothermographic element during processing is continued beyond acertain temperature. It has been desirable to provide 1 aphotothermographic element which reduces this tendency toward foggingand thus provides wider processing temperature latitude. It has alsobeen desirable to provide a photothermographic element which providesresults which are less dependent upon the presence of a so-calledactivator toning agent such as phthalazinone. Many of the reducingagents employed in photothermographic materials such asmethylene-2,2-bis(4- methyl-6-tertiary-butylphenol), as demonstrated infollowing comparative Example 24 are highly dependent upon the presencein the photothermographic material of a so-called activator toner alsoknown as a toner;ac-

celerator.

Various reducing agents have been employed in the photographic art forvarious purposes. Manyof these reducing agents, however, have not'beensatisfactory in photothermographic materials because of undesired imagediscrimination provided by such reducing agents, undesired image tone,undesired processing temperature latitude and the like.

Phenolic reducing agents have been used in photographic materials forvarious purposes. Sulfonamidophenols, for example, have been used fordifferent purposes in photographic materials such as described inCanadian Pat. No. 815,526 issued June 17, 1969; co-

pending applications Ser. No. 176,684 of Loria and Salminen, filed Aug.31, 1971; Ser. No. 176,751 of Fleckenstein and Figueras filed Aug. 31,1971 now abandoned and Ser. No. 176,752 of Fleckenstein filed Aug. 31,1971. Most phenolic reducing agents, however, have not provided improvedprocessing temperature latitude or improved developed imagediscrimination.

Accordingly, there has been a continuing need to provide improvedphotothermographic elements, compositions and processes to provideimproved processing temperature latitude and improved imagediscrimination.

SUMMARY OF THE INVENTION agents enable the omission of a so-calledactivator toning agent from the described photothermographic material.

DETAILED DESCRIPTION OF THE INVENTION A range of sulfonamidophenolreducing agents is useful in photothermographic elements andcompositions according to the invention. In photothermographic materialsa sulfonamidophenol reducing agent is useful which can-be used incombination with a heavy metal salt oxidizing agent to provide anoxidation-reduction image-forming combination and which providesimproved processing temperature latitude and improved imagediscrimination. One test which can be used in determination of suitablesulfonamidophenol reducing agents is set out in following Example 1.Another test which can be used is set out in following Examples 29-33wherein succinimide is used as an activator toning agent in place ofphthalazinone. The term sulfonamidophenol reducing agent as employedherein includes sulfonamidonaphthol reducing agents andsulfonamidophenol reducing agents. Choice of an optimumsulfonamidophenol reducing agent will depend upon the particularphotothermographic composition,

- desired image, processing conditions and the like. The

sulfonamidophenol reducing agents useful according to the invention canbe prepared employing known procedures in the art and include suchcompounds as described in Canadian Pat. No. 815,526 of Bard, issued June17, 1969. A useful class of sulfonamidophenol reducing agents accordingto the invention which ineludes sulfonamidophenols andsulfonamidonaphthols is represented by the structure:

wherein R and R are each selected from the group consisting of hydrogen;chlorine; bromine; iodine; alkyl containing one to four carbon atoms,such as methyl, ethyl, propyl and butyl; aryl containing six to 12carbon atoms such as phenyl and tolyl; arylsulfonyl containing six to 12carbon atoms, such as phenylsulfonyl; amino; hydroxy; alkoxy containingone to four carbon atoms, such as methoxy and ethoxy; and atomscompleting with R or R a naphthalene nucleus;

Z and Z are each selected from the group consisting of hydrogen;bromine; chlorine; alkyl containing one to four carbon atoms, asdescribed; aryl containing six to 10 carbon atoms, such as phenyl andtolyl; arylsulfonyl containing six to 12 carbon atoms, as described;amino; hydroxy; alkoxy containing one to four carbon atoms, such asmethoxy and ethoxy; and R SO NH- wherein R is alkyl containing one tofour carbon atoms, such as methyl, ethyl, propyl and butyl, arylcontaining 6 to 10 carbon atoms, such as phenyl and tolyl and heteroring substituents, such as thienyl, quinolinyl and thiazyl,

wherein R is p-hydroxyphenyl, p-hydroxy-3,5- dichlorophenyl orp-hydroxy-3,5-dibromophenyl;

Z is hydrogen, alkyl containing one to four carbon atoms, such asmethyl, ethyl, propyl and butyl, chlorine, bromine or RSO NH when R andR are atoms completing a naphthalene nucleus;

Z is hydrogen, alkyl containing one to four carbon atoms such as methyl,ethyl, propyl or butyl, chlo rine and bromine when R and R are otherthan atoms completing a naphthalene nucleus; at least one of Z. Z and Zis RSO,NH.

The described groups such as alkyl, alkoxy and aryl include such groupscontaining substituents which do not adversely affect the reducingproperties and desired sensitometric properties of the describedphotothermographic elements and compositions. Examples of substituentgroups which can be present are alkyl containing one to three carbonatoms such as methyl, ethyl, and propyl, chlorine, bromine and phenyl.In some cases it is desirable to avoid an amino group as a substituent.The amino group, in some cases, provides an overly active reducingagent.

One especially useful class of sulfonamidophenol reducing agents withinthe described structure are compounds of the formula:

I NHSOr-R wherein R is phenyl, naphthyl, methylphenyl, thienyl,quinolinyl, thiazyl, or alkyl containing one to four carbon atoms, asdescribed;

R is hydrogen, R SO NH, alkoxy containing one to four carbon atoms,hydroxy, alkyl containing one to four carbon atoms, bromine or chlorine;

R is hydrogen, bromine, chlorine, alkyl containing one to four carbonatoms, such as methyl, ethyl, propyl or butyl, or alkoxy containing oneto four carbon atoms, such as methoxy, ethoxy and propoxy. R R and/or Rcan contain substituent groups which do not adversely affect thereducing properties of the described sulfonamidophenol reducing agentsor the desired sensitometric properties of the photothermographicelements and materials of the invention. These substituent groups arethe same as described for generic structure 1.

Another class of sulfonamidophenol reducing agents which are useful inphotothermographic elements and compositions of the invention aresulfonamidonaphthols of the formula:

The sulfonamidophenol group in the described sulfonamidonaphthols can bein the ortho, meta or para position. The sulfonamidonaphthols andsulfonamidophenols which contain three sulfonamidophenol groups are moreactive compounds within the sulfonamidophenol reducing agent class.These sulfonamidophenols are employed for shorter developing times orwith heavy metal salt oxidizing agents which are less active than silverbehenate. ln some cases, image discrimination provided byphotothermographic materials containing the sulfonamidonaphthols andtrifunctional sulfonamidophenols is less than that provided by other ofthe described sulfonamidophenols.

Combinations of sulfonamidophenol reducing agents, as described, can beemployed in photothermographic materials and elements according to theinvention. Examples of useful sulfonamidophenol reducing agents inphotothermographic materials and elements according to the invention arelisted in the following examples. Especially useful sulfonamidophenolreducing agents include benzenesulfonamidophenol reducing agents, suchas 2,6-dichloro-4- benzenesulfonamidophenol and/or 4-benzenesulfonamidophenol.

One embodiment of the invention is in a photothermographic elementcomprising a support having 1 heavy metal salt oxidizing agent with areducing agent;

the improvement-comprising a sulfonamidophenol reducing agent, asdescribed.

The described photothermographic element comprises a photosensitivecomponent which is typically a photosensitive salt, such as aphotosensitive silver salt. It is believed that the photosensitivecomponent acts as a catalyst for the described oxidation-reductionimageforming combination. A typical concentration range ofphotosensitive component, especially photosensitive silver salt, is fromabout 0.01 to about moles of photosensitive component per mole of heavymetal salt oxidizing agent, for example, per mole of silver salt oforganic acid. An especially useful photosensitive component isphotosensitive silver halide. Useful photosensitive silver salts,however, include silver dye complexes and combinations of photosensitivesilver halide with other photosensitive silver salts. Preferredphotosensitive silver halides are silver chloride, silver bromide,silver bromoiodide, silver chlorobromoiodide or mixtures thereof. Thephotosensitive silver halide can be coarse or fine grain, very finegrain photosensitive silver halide being especially useful. Thephotosensitive silver halide can be prepared by any of the proceduresknown in the photographic art. Such procedures and forms ofphotosensitive silver halide are described, for example, in the ProductLicensing Index, Volume 92, December, 1971, publication 9232, pages107-1 10, paragraph I. The photosensitive silver halide employedaccording to the invention can be unwashed or washed, can be chemicallysensitized, can be protected against the production of fog and/orstabilized against loss of sensitivity during keeping, as described inthe above Product Licensing lndex reference.

The photothermographic elements and/or compositions according to theinvention comprise an oxidationreduction image-forming combination whichcontains an oxidizing agent, preferably a heavy metal salt oxidizingagent. The heavy metal salt oxidizing agent can be a heavy metal salt ofan organic acid such as a fatty acid which is resistant to darkeningupon illumination. An especially useful class of heavy metal salts oforganic acids is represented by the water insoluble silver salts oflong-chain fatty acids which are stable to light. Compounds which aresuitable silver salt oxidizing agents include silver behenate, silverstearate, silver oleate, silverlaurate, silver hydroxystearate, silvercaprate, silver myristate and silver palmitate. Silver salts can beemployed as the heavy metal salt oxidizing agent which are not silversalts of long-chain fatty acids. Such silver salt oxidizing agents whichare useful include, for example, silver benzoate, silver benzotriazole,silver terephthalate, silver phthalate and the like. In most cases,however, only the more reactive sulfonamidophenol reducing agents areuseful with a silver benzotriazole as the heavy metal salt oxidizingagent.

, The described sulfonamidophenol reducing agents can be employed incombination with other reducing agents in the describedoxidation-reduction imageforming combination. Suitable reducing agentswhich can be employed in combination with the sulfonamidophenol reducingagents include substituted phenols and naphthols, for example,bis-B-naphthols. Suitable bis-B- naphthols include, for example,2,2'-dihydroxy-l,1- binaphthyl, 6,6-dibromo-2,2'-dihydroxy-1 ,1

6 binaphthyl, 6,6-dinitro-2,2'-dihydroxy-l ,1 '-binaphthyl and/orbis-(2-hydroxy-1-naphthol)methane. Other reducing agents which can beemployed in photothermographic elements according tothe inventioninclude polyhydroxybenzenes such as hydroquinone, alkylsubstitutedhydroquinones such as tertiary butyl hydroquinone, methyl hydroquinone,2,5-dimethyl hydroquinone and 2,6-dimethyl hydroquinone; catechols andpyrogallols, chloro-substituted hydroquinones such as chlorohydroquinone or dichloro hydroquinone; alkoxy I substituted hydroquinonesuch as methoxy hydroquinone or ethoxy hydroquinone; aminophenoldeveloping agents, such as 2,4-diaminophenols and methylaminophenols;ascorbic acid developing agents such as ascorbic acid, ascorbic acidketals and ascorbic acid derivatives; hydroxylamine developing agents;3- pyrazolidone developing agents such as 1-phenyl-3- pyrazolidone and4-methyl-4-hydroxymethyl-1-phenyl- 3-pyrazolidone and the like.Combinations-of these reducing agents can be employed if desired.

It is often desirable to employ a so-called activator toning agent, alsoknown as an accelerator-toning agent, in the photothermographic elementsaccording to the invention to obtain a desired image. The activatortoning agent is typically useful in a range of concentration, such as aconcentration of about 0.10 moles to about 1.1 moles of activator toningagent per mole of oxidizing agent in the photothermographic element. Atypical suitable activator toning agent is a heterocyclic activatortoning agent containing at least one nitrogen atom as described inBelgian Pat. No. 766,590 issued June 15, 1971. Typical activator toningagents include, for example, phthalimide, N- hydroxyphthalimide,N-hydroxy-l,S-naphthalimide, N-potassium phthalimide, N-mercuryphthalimide, succinimide and/or N-hydroxysuccinimide. Other activatortoning agents which can be employed include phthalazinone,2-acetylphthalazinone and the like.

It is desirable, in some cases, to employ an image stabilizer and/orimage stabilizer precursor in the described elements of the invention.Typical image stabilizers or stabilizer precursors are described, forexample, in Belgian Pat. No. 768,071 issued July 30, 1971. Typicalstabilizer precursors include, for example, azothioethers and blockedazoline thione stabilizer precursors as described in this BelgianPatent.

A photothermographic element, as described according to the inventioncan contain various compounds alone or in combination as vehicles,binding agents and in various layers. Suitable materials can behydrophobic or hydrophilic. They are transparent or translucent andinclude both naturally-occurring substances such as proteins, forexample, gelatin, gelatin derivatives, cellulose derivatives,polysaccharides such as dextran, gum arabic and the like; and syntheticpolymeric substances such as water soluble polyvinyl compounds likepoly(vinyl pyrrolidone), acrylamide polymers and the like. Othersynthetic polymeric compounds which can be employed include dispersedvinyl compounds such as in latex form and particularly those whichincrease dimensional stability of photographic materials. Effectivepolymers include water-insoluble polymers of alkyl acrylates andmethacrylates, acrylic acid, sulfoalkyl acrylates, methacrylates andthose which have crosslinking sites which facilitate hardening or curingas well as those having recurring sulfobetaine units as described inCanadian Patent 774,054. Especially useful high molecular weightmaterials and resins include poly(vinyl butyral), cellulose acetatebutyrate, polymethyl methacrylate, poly(vinyl pyrrolidone),ethylcellulose, polystyrene, polyvinyl chloride, chlorinated rubber,polyisobutylene, butadiene-styrene copolymers, vinyl chloride-vinylacetate copolymers, copolymers of vinyl acetate, vinyl chloride andmaleic acid and polyvinyl alcohol.

If desired, the photosensitive silver halide employed in the describedphotothermographic elements can be prepared in situ such as described inU.S. Pat. No. 3,457,075 of Morgan et al. issued July 22, 1969.

An especially useful photothermographic element according to theinvention comprises a support having thereon (a) photosensitive silverhalide, (b) an oxidation-reduction image-forming combination comprising(i) silver behenate and/or silver stearate, with (ii)2,6-dichloro-4-benzenesulfonamidophenol and/or4-benzenesulfonamidophenol, (c) succinimide and/or N-hydroxy-l,8-naphthalimide, and (d) a polymeric binder, such as poly(vinylbutyral).

A concentration range of reducing agent can be employed in the describedphotothermographic element and/or composition of the invention. A usefulconcentration of reducing agent is typically from about 0.25 mole toabout 4 moles of sulfonamidophenol reducing agent per mole ofphotosensitive component, such as silver halide in thephotothennographic element and/or composition. In relation to theoxidizing agent employed, a useful concentration of reducing agent istypically from about 0.10 mole to about 20.0 moles of reducing agent permole of oxidizing agent, such as silver behenate or silver stearate. Ifother reducing agents are employed in combination with the describedsulfonamidophenol reducing agent, the total concentration of reducingagent is typically within the described concentration range forsulfonamidophenol.

Photothermographic elements according to the invention can containdevelopment modifiers that function as speed-increasing compounds,hardeners, antistatic layers, plasticizers and lubricants, coating aids,brighteners, spectral sensitizing dyes, absorbing and filter dyes, alsoas described in the Product Licensing 1ndex, Volume 92, December 1971,publication 9232, pages 107-1 10, paragraph I.

The photothermographic elements according to the invention can comprisea wide variety of supports. Typical supports include cellulose nitratefilm, cellulose ester film, poly(vinyl acetal) film, polystyrene film,poly(ethylene terephthalate) film, polycarbonate film and related filmsor resinous materials, as well as glass, paper, metal and the likesupports which can withstand the processing temperatures employedaccording to the invention. Typically a flexible support is employed.

Another embodiment of the invention is a photothermographic compositioncomprising (a) a photosensitive component, typically a photosensitivesilver salt such as photosensitive silver halide, with (b) anoxidation-reduction image-forming combination comprising (i) a heavymetal salt oxidizing agent with (ii) a sulfonamidophenol reducing agent,as described, and

(c) a polymeric binder, also as described, such as poly(vinyl butyral).An example of such a photothermographic composition comprises (a)photosensitive silver halide, (b) an oxidation-reduction image-formingcombination comprising (1') silver behenate or silver stearate, with(ii) a sulfonamidophenol reducing agent,

as described, such as 2,6-dichloro-4-benzenesulfonamidophenol and/or 4-benzenesulfonamidophenol, (c) an activator-toning agent which isphthalazinone, phthalimide, succinimide, and/orN-hydroxy-l,8-naphthalimide, and (d) a polymeric binder, such aspoly(vinyl butyral).

The photothermographic compositions and other compositions according tothe invention can be coated on a suitable support by various coatingprocedures including dip coating, air knife coating, curtain coating orextrusion coating using hoppers such as described in U.S. Pat. No.2,681,294 of Beguin issued June 15, 1954. If desired, two or more layerscan be coated simultaneously such as described in US. Pat. No. 2,761,791of Russell issued Sept. 4, 1956 and British Pat. No. 837,095.

Spectral sensitizing dyes can be used in the describedphotothermographic elements and compositions of the invention to conferadditional sensitivity to the elements and compositions of theinvention. Useful sensitizing dyes are described, for example, in theProduct Licensing Index, Volume 92, December 1971, publication 9232,pages 107-110, paragraph XV.

After exposure of the described photothermographic element according tothe invention, typically to visible light, the resulting latent imagecan be developed merely by overall heating the element to moderatelyelevated temperatures. This merely involves heating the describedphotothermographic element overall from about C. to about 250C. such asfor about 0.5 seconds to about 60 seconds. By increasing or decreasingthe length of time of heating, a higher or lower temperature within thedescribed range can be employed depending upon the desired image. Adeveloped image is typically produced within several seconds, such asabout 0.5 seconds to about 60 seconds. A processing temperature of about110C. to about C. is especially useful.

Any suitable means can be used for providing the desired processingtemperature range. The heating means can be a simple hot plate, iron,roller or the like.

Processing is usually carried out under ambient conditions of pressureand humidity. Conditions outside normal atmospheric pressure andhumidity can be employed, if desired.

If desired, one or more components of the photothermographic element canbe in one or more layers of the element. For example, in some cases itcan be desirable to include certain percentages of the reducing agent,activator toner, image stabilizer and/or stabilizer precursor in aprotective layer over the photothermographic element. This in some casescan reduce migration of certain addenda in the layers of thephotothermographic element.

The following examples are included for a further understanding of theinvention.

EXAMPLE 1 poly(vinyl butyral) behenic acid silver behenate sodiumbromide l-(2H)phthslazinone acetone-toluene (1:1 parts by volume) Theresulting dispersion, in the absence ofa reducing I Time agent, iscoated on a polyethylene coated paper sup- Example 'mW/FQB port at 0.6millimoles of silver per square foot. A 0.02 3 I molar solution of4-(N-Methylsulfonamido)phenol in 5 4 2 acetone-alcohol is coated ontothe resulting element at RHmasomH 4 6 milligrams per square decimeter.The resulting 5 R"=C,HtSO NH 3 photothermographic element is permittedto dry. It IS 6 R,,=p CH3C6Hs0:NH ++l+ then sensltometrlcally exposed totungsten light and 4 then overall heated by contacting a heated metalblock 7 REP NO=CQH4SO1NH- for 2 seconds at 115C. 3 e= H A dense blackimage having a maximum density of 9 RL 4 0.63 and a minimum density of0.18 is obtained. 'HfiL/O l0 R=cll,;R-=cH,so NH EXAMPLE 2 llR=CH3R=CGH5S0,NH

This is a comparative example. E H so NH The procedure set out inExample 1 is repeated with 5 4 the exception that 4-aminophenol isemployed as a re- 13 B 5 Z H +++/0 ducing agent in place of 4-(N- 14RB=CI;RB=P BICBH4SOINH Hm methylsulfonamido)phenol. The concentration of4- a w 2 aminophenol is 0.02 molar. The coating coverage of R =R ++l+4-aminophenol is 5 milligrams per square decimeter. 1 a= w= l= 2 Uponsensltometrlc exposure of the pho tothermo .25 l 7 RECHVSONW ++l+graphic element and overall heating at 115 C. as de- 4 scribed inExample 1, an image appears in less than one 7 V r g Second followed yrapid formation of dense e The In each example, other substituents arehydrogen unresulting image is brown in color. less indicated otherwise.

W Each photothermographic element in Examples 3-17 EXA P 3 7 produced animage with acceptable image discriminab W V v tion The procedure set outin Example I is repeated with EXAMPLES 1843 the Fp t that thesPtfon-amidophenol teducltfg These examples demonstrate aphotothermographic agents llsted the followmg Table p y elementaccording to the invention in the absence of an place of the described4-(N- activator toning agem methytsulfonamldo)phenol- Heating ttme ofthe P The procedure set out in Example 1 is repeated with thetmogt'aphtcelement after sensttometnc PQ 1S the exception that phthalazinone isomitted. The procelisted in Table l as well as the degree of imagedlscrimidure is also repeated employing a Q02 molar comenation and fogformation A single P indicates a 10w 40 tration of phthalazinone in thephotothermographic eldensity (under two Pluses mdtcate an Image ofement. The results of Examples 18-23 with and without moderate densityand three pluses indicate phthalazinone are set out in following TableII. In each an m g of h g i y (Over Zero indicates R0 instance thephotothermographic element is heated for image fog. the designated timeat 150C.

m "Table Ii Without Toner With Phthala zinone Example Compound Time TimeNo. of (seconds) Image Hue (seconds) lmage Hue 18 Example 5 l -Hl-Neutral 5 -Hl- Neutral l9 Example 7 l -llt- Brown 3 +H- Neutral 20Example l0 3 -ll- Brown 3 -ll- Brown 2l Example 12 2 -l+l- Brown 4 +l-l-Neutral 22 Example 13 2 -lH- Neutral 2 -l-l-+ Neutral "23 l -ll-+-Neutral too actlve TABLE I O'H W OH R' I R R HN-BOzCJh It should benoted in these examples that the image appears as rapidly in the absenceof the toning agent as in its presence and that the images are equallydense although they are not as neutral in hue in each example.

latent image is developed by overall heating the photothermographicelement by contacting it with a heated metal block at 115C. or 150C. forthe time specified in following Table IV.

Table IV Example Toner- Temp Time No. Compound Accelerator (C.)(seconds) Dmax Dmin 25 Butylsulfonamidophenol 1 2 1.05 .10

Phthalazinone 26 Butylsulfonamidophenol 150 1 1.60 .09

Phthalazinone 27 l.1'-Binaphth01 Phthalazinone 1 15 .88 .16

(Comparative Example) 28 l.l-Binaphthol Phthalazinone 150 5 1.90 .19

(Comparative EXAMPLE 24 This is a comparative example.

The procedure set out in Example 18 is repeated with the exception thatmethylene-2,2'-bis(4-methyl-6-tertiary-butylphenol) is employed in placeof the described reducing agent. The results produced aftersensitometric exposure and overall heating at 150C. are set out in thefollowing Table 111.

Table 111 Without Toner Example) h lt is concluded from the results inExamples 25-28 20 that the sulfonamidophenol reducing agent of Example25 produces a desired maximum density in shorter processing time thanthe compound of Example 27. It is also observed that the compounds ofExample 25 provides greater processing temperature latitude.

EXAMPLES 29-37 The procedure set out in Example 1 repeated with WithPhthalazinone Example Time: Time No. (seconds) lmage Hue (seconds) Image24 1 1 Tan 5 +1-1- Hue Dark Brown EXAMPLES 25-28 Ten cc of a 2.5% byweight poly(viny1 butyral) so1ution in acetone/toluene containing 0.4millimoles of the reducing agent designated in Table IV and 0.08 to 0.14millimoles of l-(2l-l)-phthalazinone is overcoated onto a photosensitiveelement containing behenic acid, si1-. ver behenate and silver bromidein a poly(vinyl butyral) binder. This photosensitive element is preparedby mixing the noted components and coating the resulting compositiononto a film support at 0.60 millimoles of silver per square foot. Theresulting photothermo graphic element is sensitometrically exposed totung sten light through a high contrast image. The resulting theexception that phthalazinone is replaced with an equal molarconcentration of succinimide and a concentration of one mole of thesulfonamidophenol reducing agent described in following Table V isemployed for each 2 moles of silver behenate present in thephotothermographic element. The photothermographic element issensitometrically exposed to tungsten light and then overall heated atthe temperatures and times described in following Table V. The resultsemploying this procedure are set out in following Table It is concludedfrom this dttifi'i satisfactory image .dsnsity btins a v s aa zmeqia 9Example 3 13 C. and yet fog density is not excessive at temperatures ashigh as 140C. This is increased processing temperature latitude whichmany reducing agents do not provide. With many reducing agents fog isobserved almost as soon as desired image density is produced.

EXAMPLES 38-63 V The procedure set out in Example 1 is repeated usingTABLE VI Example Temp. Time number Compound. C.) (seconds) Image densityH -N S 020011 I NH S OzCflH5 as (|)H 150 5 1.30.

NH 5 OzCsHs 40 OIII 150 3 1.40.

H CaHg-S OzN OCH:

1 NH-S Or-CsHs 41 n! 150 1 0.51 (high fog).

O NH 5 02C7H7 NH: A,

42 OH 150 1 1.02 (overly active).

NHS OzC|oHa l NIL- S 02- 0 44 (])H 150 No image.

NH S orcuHs H CaHsSOzN- OCH:

I IHS OzCsH TABLE VLdontiriuef' Example Temp. Time number Compound 0.)(seconds) Image density '46 (RH mm" 7 V 150 3 0.38.

I NH- 5 02C1H1 47 OH 150 1 1.47 (high fog).

NH S 020.11;

NH S 02CuH 49 131 150 1 1.48 (also active developer, no accelerator).

\/-NH S O1CuHs 50 OH OH 150 2 1 14 1 O I NH-SO -SOz-NH 5l OH OH 150 2064 Br- Br Br Br I I NH-SO -B0r-NH 52 RISE! I OH 150' 1 L2? 01- C1 C1 C1N b'm 53 NHS 0100115 150 2 1.20.

54 (3H OH 150 3 1.38.

@NH-S Ov-$ Oz-NH 55 0H OH 150 1 1.11.

01 C1 C1 C1 l l HN- S O S OrNH TABLE \IContinued Example Temp Timenumber Compound C.) (seconds) Image density OzN H O NS O O COzCH;

H O; N-S- HzC C02CH3 59 (RH 150 1 D 1.0 (high fog).

I NH;

60 0H 135 Good image by itself and with N-hydroxynaphthalimide at 135 C.C1 C1 NH S O.

61 OH 135 Good 'imag with phthalazinone at 135 C.

- 160 Good image with phthalimlde at 160 C. 01 C1 CH -N 1 I l I NH S O sNHIHJ CH;

62 OH 135 Good image with phthalazinone, phthalimideN-hydroxynap'hthalimide and suocinimide at 135 C. C1- G1 I N HSI 02 I Il 63 OH 160 Weak image with phthalazi-none. N-hydr ynaphthalimlde andsuocinimlde at 100 0. Cl C] EXAMPLE 64 A silver behenate-behenic aciddispersion is prepared by ball-milling the following components forabout 1 12 hours:

Silver behenate 168.0 g Behenic acid 64.0 g Lithium stearate 16.8 gPoly(vinyl butyral) 120.0 g Acetone-toluene (lzl parts by volume) 2.01 1

63.0 ml. of this dispersion are mixed with 20.0 ml. of silverbromoiodide dispersed in poly(vinyl butyral) (6 liters/mole of silver)and with the following components:

Acetone-toluene'methanol (lilzl parts by 8.0 ml

volumelsolution containing 0.5% by weight of N-hydroxy-1.8-naphthalimidev Acetonemethanol solution (33:1 parts by volume) 6.2 ml

. containing3-carboxy-methyl-5-[(3-methyl-2-thiazolidinylidene)-lmethylethylidenelrhodanineand 0.01% by volume triethylamine Acetone solution containing 10% byweight 10.0 ml

2,G-dichloro-4-benzenesulfonamidophenol Acetone 18.0 ml

The resulting composition is coated and permitted to dry on a papersupport at 8.61 mg. of silver per square decimeter to provide aphotothermographic element. This photothermographic element is exposedsensitometrically to tungsten light for 0.5 seconds and then heatedoverall by contacting the element with a heated metal block for 2seconds at 140C. A developed image results. The element is then held influorescent room: light under ambient conditions for 48 hours. Theresulting image is black with a beige background.

It is often desirable to provide an overcoat on the describedphotothermographic elements. The overcoat can comprise polymericmaterials which can protect the photothermographic element againstundesired fingerprint marks and abrasion. One overcoat which is suitablecomprises a combination of gelatin with a polyhydric alcoholplasticizer, such as 3-methyl-2,4-j pentanediol and/or glycerin, or apolymeric latex com-f prising at least one 2-acetoacetoxyethylmethacrylate group, such as described in US. Pat. No. 2,960,404 ofMilton et a1. and/or US. Pat. No. 3,488,704 of Smith.

2. A photothermographic element as in claim 1 wherein saidsulfonamidophenol reducing agent is a compound, selected from the grouprepresented by the formula:

wherein R and R are each selected from the group consisting of hydrogen,chlorine, bromine, alkyl containing one to four carbon atoms, arylcontaining six to 12 carbon atoms, amino, hydroxy, alkoxy containing oneto four carbon atoms, and atoms completing with R or R a naphthalenenucleus;

Z and Z are each selected from the group consisting of hydrogen,bromine, chlorine, alkyl containing one to four carbon atoms, arylcontaining six to 10 carbon atoms, arylsulfonyl containing six to 12carbon atoms, amino, hydroxy, alkoxy containing one to four carbonatoms, and R SO NH wherein R is alkyl containing one to four carbonatoms, aryl containing six to 10 carbon atoms, thienyl, quinolinyl,thiazyl,

' wherein R is p-hydroxyphenyl, p-hydroxy-3,S-dichlorophenyl orp-hydroxy-3,S-dibromophenyl;

Z is hydrogen, alkyl containing one to four carbon atoms, chlorine,bromine or RSO NH when R and R are atoms completing a naphthalenenucleus;

Z is hydrogen, alkyl containing one to four carbon atoms, chlorine orbromine when R and R are other than atoms completing a naphthalenenucleus;

at least one of Z, Z and Z is RSO NH.

3. A photothermographic element as in claim 1 wherein saidsulfonamidophenol reducing agent is a compound of the formula:

l NHSOz-IR wherein R is phenyl, naphthyl, methylphenylthienyl,quinolinyl, thiazyl, or alkyl containing one to four carbon atoms;

R is hydrogen, -NHSO R alkoxy containing one to four carbon atoms,hydroxy, alkyl containing one to four carbon atoms, bromine or chlorine;

R" is hydrogen, bromine, chlorine, alkyl containing one to four carbonatoms or alkoxy containing one to four carbon atoms.

4. A photothermographic element as in claim 1 wherein saidsulfonamidophenol is a compound of the formula:

5. A photothermographic element as in claim 1 wherein saidsulfonamidophenol reducing agent is 2,6-dichloro-4-benzene-sulfonamidophenol.

6. A photothermographic element as in claim 1 wherein saidsulfonamidophenol reducing agent is 4- benzenesulfonamidophenol.

7. A photothermographic element as in claim 1 also comprising anactivator-toning agent which is phthalazinone, phthalimide, succinimideor N-hydroxy- 1,8-naphthalimide.

8. A photothermographic element as in claim 1 wherein saidphotosensitive component is photosensitive silver halide.

9. A photothermographic element comprising a support having thereon a.photosensitive silver halide,

b. an oxidation-reduction image-forming combination comprising i. silverbehenate, with ii. 2,6-dichloro-4-benzenesulfonamidophenol or4-benzenesulfonamidophenol,

c. N-hydroxy-l,S-naphthalimide, and

d. a polymeric binder.

10. A photothermographic element as in claim 1 comprising about 0.25 toabout 4.0 moles of said sulfonamidophenol reducing agent per mole ofsaid photosensitive component.

11. A photothen'nographic composition comprising a. a photosensitivecomponent, with b. an oxidation-reduction image-forming combinationcomprising i. a heavy metal salt oxidizing agent with ii. asulfonamidophenol reducing agent, and

c. a polymeric binder.

12. A photothermographic composition as in claim 11 comprising about 0.4to about 2.0 moles of said sulfonamidophenol reducing agent per mole ofsaid photosensitive component.

13. A photothermographic composition as in claim 11 also comprising anactivator-toning agent which is phthalazinone, phthalimide, succinimideor N-hydroxy- 1,8-naphthalimide. 5 14. A photothermographic compositioncomprising a. photosensitive silver halide, b. an oxidation-reductionimage-forming combination comprising i. silver behenate, with ii.2,6-dichloro-4-benzenesulfonamidophenol or 4-benzenesulfonamidophenol,c. an activator-toning agent which is phthalazinone,

phthalimide, succinimide, or naphthalimide, and

d. a polymeric binder.

15. A photothermographic composition comprising a. photosensitive silverhalide, b. an oxidation-reduction image-forming combination i. silverbehenate, with ii. a reducing agent represented by the formula:

NHSO2@ and c. a polymeric binder.

16. A process of developing a latent image in an exposedphotothermographic element comprising a support having thereon aphotosensitive component, an oxidation-reduction image-formingcombination comprising a heavy metal salt oxidizing agent with asulfonamidophenol reducing agent and a polymeric binder, comprisingheating said element from about 80C. to about 250C.

17. A process of developing a latent image as in claim 16 wherein saidphotothermographic element is heated from about 80C. to about 250C. forabout 0.5 to about 60 seconds.

18. A process of developing a latent image in a photothermographicelement comprising a support having thereon a. photosensitve silverhalide,

b. an oxidation-reduction image-forming combination comprising i. silverbehenate, with ii. 2,6-dichloro-4-benzenesulfonamidophenol or4-benzenesulfonamidophenol,

c. N-hydroxy-l,S-naphthalimide, and

d. a polymeric binder,

comprising heating said element from about 80C. to

about 250C. for about 0.5 to about seconds.

N-hydroxy-1,8-'

mg C UNITED STATES PATENT CFFIICEX 'CERTIFECATE CF CORRECTION Patent No.3,801,321 Dated p il 2, 197 1 Inventofls) Francis J. Evans and Donald F.McLaen- It is certified that error appears in the above-identifiedpatent; and that said Letters Patent are hereby corrected as shownbelow:

F'- "w a In the Abstract, lines L-S, after "reducing" delete"photothermographic' and insert ---agents---.

In the Abstract, line 5, "photobermog-raphic" should readphotothermographic- 1 R Column 10, Example 12, "7=CH ;R :C H' SO NH-"should Column 12, line 65, "1,22" should read --l.,22-=-.

Column 15, Example #8, the structure 0H NHSO2C6H5 should read Column 15,Example M9, the structure NHSO C H NHSO2C6H5 should read Page .2

5% UNITED STA'EES PATENT OFFICE CERTiFICATE OF CORRECTION Patent No.3,801,321 Dated April 97 Inventofls) Francis Evans and Donald F. McLaenIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 20, line 29, the structure E should read mmso Column 20, line 36,the structure gNHso should read RNHSO @Q@.

Column 22, line 46, photosensitve" shouldread --photo'sensitive---. I

Signed and sealed this 15th day of October 1974.

- (SEAL) Attest:

MCCOY M. GIBSON JR. C. MARSHALL DANN Commissioner of Patents AttestingOfficer

2. A photothermographic element as in claim 1 wherein saidsulfonamidophenol reducing agent is a compound, selected from the grouprepresented by the formula:
 3. A photothermographic element as in claim1 wherein said sulfonamidophenol reducing agent is a compound of theformula:
 4. A photothermographic element as in claim 1 wherein saidsulfonamidophenol is a compound of the formula:
 5. A photothermographicelement as in claim 1 wherein said sulfonamidophenol reducing agent is2,6-dichloro-4-benzene-sulfonamidophenol.
 6. A photothermographicelement as in claim 1 wherein said sulfonamidophenol reducing agent is4-benzenesulfonamidophenol.
 7. A photothermographic element as in claim1 also comprising an activator-toning agent which is phthalazinone,phthalimide, succinimide or N-hydroxy-1,8-naphthalimide.
 8. Aphotothermographic element as in claim 1 wherein said photosensitivecomponent is photosensitive silver halide.
 9. A photothermographicelement comprising a support having thereon a. photosensitive silverhalide, b. an oxidation-reduction image-forming combination comprisingi. silver behenate, with ii. 2,6-dichloro-4-benzenesulfonamidophenol or4-benzenesulfonamidophenol, c. N-hydroxy-1,8-naphthalimide, and d. apolymeric binder.
 10. A photothermographic element as in claim 1comprising about 0.25 to about 4.0 moles of said sulfonamidophenolreducing agent per mole of said photosensitive component.
 11. Aphotothermographic composition comprising a. a photosensitive component,with b. an oxidation-reduction image-forming combination comprising i. aheavy metal salt oxidizing agent with ii. a sulfonamidophenol reducingagent, and c. a polymeric binder.
 12. A photothermographic compositionas in claim 11 comprising about 0.4 to about 2.0 moles of saidsulfonamidophenol reducing agent per mole of said photosensitivecomponent.
 13. A photothermographic composition as in claim 11 alsocomprising an activator-toning agent which is phthalazinone,phthalimide, succinimide or N-hydroxy-1,8-naphthalimide.
 14. Aphotothermographic composition comprising a. photosensitive silverhalide, b. an oxidation-reduction image-forming combination comprisingi. silver behenate, with ii. 2,6-dichloro-4-benzenesulfonamidophenol or4-benzenesulfonamidophenol, c. an activator-toning agent which isphthalazinone, phthalimide, succinimide, or N-hydroxy-1,8-naphthalimide,and d. a polymeric binder.
 15. A photothermographic compositioncomprising a. photosensitive silver halide, b. an oxidation-reductionimage-forming combination i. silver behenate, with ii. a reducing agentrepresented by the formula:
 16. A process of developing a latent imagein an exposed photothermographic element comprising a support havingthereon a photosensitive component, an oxidation-reduction image-formingcombination comprising a heavy metal salt oxidizing agent with asulfonamidophenol reducing agent and a polymeric binder, comprisingheating said element from about 80*C. to about 250*C.
 17. A process ofdeveloping a latent image as in claim 16 wherein said photothermographicelement is heated from about 80*C. to about 250*C. for about 0.5 toabout 60 seconds.
 18. A process of developing a latent image in aphotothermographic element comprising a support having thereon a.photosensitve silver halide, b. an oxidation-reduction image-formingcombination comprising i. silver behenate, with ii.2,6-dichloro-4-benzenesulfonamidophenol or 4-benzenesulfonamidophenol,c. N-hydroxy-1,8-naphthalimide, and d. a polymeric binder, comprisingheating said element from about 80*C. to about 250*C. for about 0.5 toabout 60 seconds.